Community-based solid waste bank program for municipal solid waste management improvement in Indonesia: a case study of Padang city

Journal of Material Cycles and Waste Management - Indonesia has a regulation UU No. 18/2008 which changes the paradigm from waste dumping to recycling. The purpose of this study is to understand...     

Spatial simulation and LCA evaluation on the plastic waste recycling system in Tianjin

With the rapid economic development in China, the amount of plastic waste (PW) generated has greatly increased and much of the waste is currently not treated. To reduce greenhouse gas (GHG) emissions from recycling of PW, we estimated the PW flow and considered methods to improve the household PW recycling system in Tianjin by adjusting processes during transportation and establishing a PW recycling factory in Zi’ya Industrial Park. The goal of the study was to identify reasonable improvements for the recycling system and clarify the environmental load. Geographic information system (GIS) technology was used to simulate transport processes for comparing GHG emissions from the transport processes between the present case and an improved case. Life cycle assessment (LCA) was used to compare GHG emissions between a projected scenario and a baseline scenario. Estimated GHG emissions during transport processes in the improved case were reduced by about 12,197 t CO₂ eq per year compared to the present case, equivalent to about 65.9 % of the total emissions in the present case. GHG emissions in the projected scenario were about 101,738 t CO₂ eq less per year than the baseline scenario, equivalent to about 75.5 % of the total emissions in the baseline scenario.     

Characterization of trace constituents in landfill gas and a comparison of sites in Asia

Because landfill gas (LFG) contains an abundance of methane, the utilization of LFG as a renewable energy source is becoming popular in many countries. LFG, however, contains various trace constituents, some of which may pose problems during utilization. For example, siloxanes and halogenated volatile organic compounds (VOCs) can cause difficulties when present in the fuel of gas engines. In addition, many VOCs and mercury have harmful effects on human health, especially on the health of workers at landfill sites and people living near the landfills. Energy recovery from LFG is expected to make great progress in the near future, particularly in Asia, but we found little information on the trace constituents of LFG in this region. Therefore, we sought to characterize the trace components in LFG generated in two landfill sites in China and one site in Japan, to determine the typical concentrations of these trace components in LFG, and to compare their concentrations among landfill sites in Asia. We concluded that the trace components in LFG at the sites studied were mainly siloxanes generated from sewage sludge and harmful benzene, toluene, ethylbenzene, and xylene compounds from petroleum products.     

Degradation of monofluorophenols in water irradiated with gaseous plasma

Decomposition of aqueous monofluorophenols (MFPs) was investigated by contact glow discharge electrolysis (CGDE). During CGDE, both MFPs and the corresponding total organic carbon (TOC) in water were consumed smoothly, suggesting that carbon atoms of benzene nucleus could be eventually mineralized to inorganic carbon (IC). And all the fluorine atoms in the MFPs were equally converted to fluoride ions. Based on the primary intermediates from each starting materials, it showed that aromatic hydroxylation preferentially occurred at the para- or ortho- position to the phenolic OH group of each MFPs. The disappearance of both MFPs and TOC followed the first-order rate law. The apparent rate constants for the decay of MFPs were independent from the pK_a values of MFPs.     

Effect of dietary protein on the distribution of cadmium,zinc and copper in rats following the oral administration of cadmium

Cadmium, 100 μg/rat/day, was administered orally 100 times (total amount of Cd administered, 10 mg), under conditions of low protein intake. The total amount of Cd in the liver and kidneys was as follows: females fed 20% protein diets > females fed 5% protein diets > males fed 20% protein diets ≒ males fed 5% protein diets. A decreased Zn concentration was found in the liver of males and the pancreas of males and females fed with the 5% protein diet. The Cu concentration in the kidneys was markedly influenced by low protein intake.     

Activity and emission inventory of open waste burning at the household level in developing countries: a case study of Semarang City

Journal of Material Cycles and Waste Management - In this study, total burned household waste and the potential emissions released from waste burning in Semarang City, Indonesia, were estimated....     

Feasibility study of a passive aeration reactor equipped with vertical pipes for compost stabilization of cow manure.

Pilot-scale composting was carried out with cow manure to evaluate the performances of two passive aeration systems: a conventional passive aeration system equipped with horizontal pipes and an unusual passive aeration method based on air delivery by means of vertical pipes. The effects of both types of passive aeration apparatus were investigated in order to determine the degree of composting rate by continuously monitoring temperature, moisture content, organic matter, electrical conductivity, pH and C/N ratio in the piles. Temperatures in the range of thermophily (55-65 degrees C) were reached in all runs within 1-2 days then lasting for about 1 week, a span long enough for pathogen abatement. Results suggest that passive aeration carried out by vertical pipes is more effective for air delivery into compost piles than conventional passive aeration of air adduction with horizontal pipes. The variation in the number of vertical pipes was revealed to be an important parameter for the control of composting rate and temperature. Composting rates estimated from the heat balance equation were substantially in agreement with those computed through the conversion ratio of total organic matter decrement. The conversion ratios and composting rates obtained in this study using passive aeration with vertical pipes were well aligned with those found using forced air delivery systems.     

Synthesis of Short-chain-length/Medium-chain-length Polyhydroxyalkanoate (PHA) Copolymers in Peroxisome of the Transgenic Arabidopsis Thaliana Harboring the PHA Synthase Gene from Pseudomonas sp. 61-3

In this paper, the photosynthetic production of short-chain-length/medium-chain-length polyhydroxyalkanoate (PHA) copolymers is reported. The wild-type and highly active doubly mutated PHA synthase 1 (S325T/Q481K, abbreviated ST/QK) genes from Pseudomonas sp. 61-3 were introduced into Arabidopsis thaliana. Peroxisome targeting signal 1 (PTS1) was used to target PHA synthases into the peroxisome to synthesize PHA from the intermediates of the β-oxidation pathway. The transgenic Arabidopsis produced PHA copolymers consisting of 40–57 mol% 3-hydroxybutyrate, 21–49 mol% 3-hydroxyvalerate, 8–18 mol% 3-hydroxyhexanoate, and 2–8 mol% 3-hydroxyoctanoate. The maximum PHA contents were 220μ g/g cell dry weight (cdw) in leaves, and 36μ g/g cdw in stems, respectively. The expression of the ST/QK mutated PHA synthase in leaves gene did not lead to significant difference in PHA content and monomer composition of PHAs, compared to the wild-type PHA synthase gene, suggesting that the supply of monomers may be a rate-determining step of PHA biosynthesis in the peroxisome. However, in stems, there were significant differences dependent on whether the wild-type or ST/QK mutated PHA synthase was expressed. These results suggest that tissue-specific monomer availability is important in determining the final mol% composition of PHA copolymers produced by the peroxisome in plants.     

Relationships between bacterial tolerance levels and forms of copper and zinc in soils

The effects of various fractions of copper (Cu) and zinc (Zn) on soil bacteria were evaluated by the heavy metal tolerance level of the bacterial community (IC50) in soil samples collected near a mine. The IC50 values had no relationship with the total concentrations of Zn and Cu in the soils, but were weakly correlated with the 0.05 M CaCl2-extractable form of each metal in the soils (Cu: R2 = 0.670, p < 0.01; Zn: R2 = 0.453, p < 0.05). It was found that the IC50 correlated strongly with the total concentration of each metal in the extracts from water-saturated soil samples, described below as "soil solution" (Cu: R2 = 0.789, p < 0.01; Zn: R2 = 0.617, p < 0.01). The speciation of these metals in the soil solutions was estimated using an equilibrium thermodynamic computer model, SOILCHEM. Simulated free Cu ion ranged from 18 to 98% of total Cu, and organic complexes of Cu ranged from < 1 to 56%. In all samples, Zn existing as the free ion was estimated to be more than 80% of total Zn in the soil solutions. The IC50 values were also correlated with the estimated free metal ion activities, but with slightly lower correlation coefficients than found for total concentration in the soil solutions (Cu: R2 = 0.735, p < 0.01; Zn: R2 = 0.610, p < 0.01). The results suggest that not only high metal ion activities, but also total dissolved metal concentrations in soil solutions may affect the bacterial community.     

Kinetics on the decomposition of polychlorinated biphenyls with activated carbon-supported iron

The process of destroying polychlorinated biphenyls (PCBs) generates exhaust gases that contain low quantities of PCBs, which cannot be disposed of easily. Activated carbon (AC) can be used to adsorb residual PCBs after disposal of high-level PCBs. We examined the chemical reactivity of AC-supported iron as a catalyst to decompose PCB-153, and varied three decomposition parameters (temperature, time and iron concentration) under an atmosphere of either air or N(2). We measured the Brunauer-Emmett-Teller (BET) surface area and pore volume of AC to assess the adsorption capacity of AC before and after decomposition. At low temperatures the adsorption process was more important than the decomposition process. The decomposition process was completed within 30 and 60 min under air and N(2), respectively. The efficiency of PCB-153 decomposition at 350 degrees C for 120 min was approximately 100.0% and 97.1% under air and N(2), respectively. Analysis of inorganic chloride ions revealed that PCB-153 was effectively destroyed during decomposition. The differences between decomposition under air and N(2) reflected differences in BET surface and pore volume.